Ultrasonic Device Vibration Plate Pb Diffusion Control

The patent changes the material composition parameters by introducing a SiO2 layer with specific thickness (50-200 nm) between the membrane and barrier layer. This parameter change allows the barrier layer to have sufficient bending rigidity for Pb diffusion prevention while the overall vibration plate thickness remains controlled, maintaining resonance frequency within acceptable ranges.

The patent uses a composite structure consisting of a membrane layer, a SiO2 intermediate layer, and a barrier layer. This composite material approach allows each layer to contribute different properties: the membrane provides flexibility, the SiO2 layer provides mechanical support and prevents Pb diffusion, and the barrier layer provides additional protection. This resolves the contradiction by distributing functions across multiple layers rather than relying on a single thick barrier layer.

The patent employs a composite structure where the SiO2 intermediate layer and barrier layer work together to prevent Pb diffusion while allowing the membrane to vibrate efficiently. The SiO2 layer has appropriate bending rigidity to prevent Pb diffusion, while the membrane maintains its flexibility for efficient vibration. This composite approach resolves the contradiction by separating the diffusion prevention function from the vibration function.

The SiO2 layer acts as an intermediary between the membrane and the barrier layer. This intermediate layer prevents direct contact between the membrane and barrier layer, allowing each to perform its specific function optimally: the membrane vibrates efficiently while the SiO2 and barrier layers prevent Pb diffusion. The intermediary layer mediates the mechanical and chemical interactions to achieve both vibration efficiency and diffusion prevention.